A train consist often includes a lead locomotive and at least one trailing locomotive. The lead locomotive, although generally located at the leading end of the consist, can alternatively be located at any other position along its length. The lead locomotive generates operator and/or autonomous control commands directed to components of the lead and trailing locomotives. A typical locomotive of a consist will have a prime mover power source that includes a diesel engine and an alternator or generator that converts rotational output of the diesel engine into electrical power. The term “prime mover” is generally used to refer to the source of power used primarily for generating a tractive effort used in moving the vehicle. A prime mover power source may also provide power for parasitic or auxiliary loads that do not contribute to the tractive effort, such as air compressors, traction motor blowers, and radiator fans. In some cases an additional auxiliary power source is included on the locomotive to provide the power needed for parasitic or auxiliary loads. Electrical power output by the prime mover power source is used primarily to drive electric traction motors, which convert the electrical power back into rotational output that drives the axles and wheels of the locomotive. A typical locomotive may have two trucks that support the body of the locomotive, with each truck including two or three axles, and each axle being driven by one of the electric traction motors.
Tractive power for the locomotive is supplied by the traction motors. Each traction motor may be an alternating current (AC) traction motor or a direct current (DC) traction motor. The diesel engine drives an alternator/rectifier that provides the prime mover electrical power to an electrical power bus. The prime mover electrical power from the alternator/rectifier is DC power that is then converted to provide electrical power in the appropriate form for the traction motors. When AC traction motors are used, one or more inverters receive the prime mover DC electrical power from the electrical power bus and supply AC power to one or a plurality of locomotive traction motors to propel the locomotive. When DC traction motors are used, DC chopper circuits receive a constant DC electrical power from the electrical power bus on the same locomotive and convert this constant DC electrical power into a variable DC electrical power source appropriate for each DC traction motor. The conversion of DC electrical power for use by DC traction motors includes using a switching technique known as pulse width modulation (PWM). Each of the locomotive traction motors on a locomotive propel the locomotive in response to the prime mover electrical power.
Communication between the lead and trailing locomotives can involve a hard-wired multi-unit (MU) cable, which carries signals indicative of a desired power level for the consist. The MU cable includes several wires that carry signals indicative of different throttle notch settings (predefined discrete power levels). Most of these signals are binary indicators that either provide a voltage or no voltage to the wires. Known methods for controlling a consist of at least first and second locomotives include providing control signals from a lead locomotive over the MU cable to command discrete operating modes for each locomotive in a consist. Such a method is disclosed in U.S. Pat. No. 7,021,588 that issued to Hess, Jr. et al. on Apr. 4, 2006 (“the '588 patent”). The method in the '588 patent comprises receiving a control command and determining a power operating mode of the first locomotive and a power operating mode of at least the second locomotive as a function of the control command and an optimization parameter.
Although the system of the '588 patent may have improved communication between multiple locomotives in a consist, the system may still be problematic. In particular, the system may be limited to communicating power operating requirements and control signals to each locomotive in a consist, but without the capability of actually sharing electrical power generated by power sources on each of the locomotives.
The power sharing method of the present disclosure solves one or more of the problems set forth above and/or other problems in the art.